●下面关于光纤的论述中，错误的是(21)。

（46）

●In computer science ,a data (72) is a way of storing data in acomputer so that it can be used efficiently.

●设信道的码元速率为600波特，采用4相DPSK调制，则其数据速率为 (22) b/s。

●A (73) is a named memory block. By using its name, we can refer to the data stored in the memory block.

●路由器Console端口默认的数据速率为 (23)。

●要判断16位二进制整数x的低三位是否全为0，则令其与十六进制数0007进行(14)运算，然后判断运算结果是否等于0。

●The term, (74) loop, refers to a loop that is contained within another loop.

● (15)专门用于翻译汇编语言源程序。

●The (75)is designed specifically as a security system for preventing unauthorized communications between one computer network and another computer network.